Tension mechanism for sewing-machines.



F. s@ WOODHEAD.

TENSION MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JULY 14, 1910.

995,312. Patented June 13, 1911.

WITNESSES: INVENTOR j mi z od eaci ATTORNEY TNT 1Q FRANK S. WOODHEAD, 0FBRIDGEPORT, CONNECTICUT, ASSIGNOR TO THE SINGER MAN- UFACTURING COMPANY,OF ELIZABETH, NEW JERSEY, A CORPORATION OF NEW JERSEY.

TENSION MECHANISM FOR SEWING-MACHINES.

Specification of Letters Patent. Patented June 13, 1911.

Application filed July 14, 1910. Serial No. 571,879.

To all whom it may concern;

Be it known that I, FRANK S. WOODHEAD, a citizen of the United States,residing at Bridgeport, in the county of Fairfield and State ofConnecticut, have invented certain new and useful Improvements inTension Mechanism for Sewing-Machines, of which the following is aspecification, reference be ing had therein to the accompanyingdrawings.

This invention relates to improvements in thread-tension devices forsewing machines, especially that variety commonly termed thread-checks,and may be employed singly or in connection with some other form oftension device as in the present instance.

Prior to this invention it has been common to pass the needle threadacross the flat surface of a permanently secured tension element andproduce the desired tension by the employment of a coacting fiat springor other yieldingly mounted element; but when the thread consists ofclosely twisted strands, as is commonly the case, the action of suchtension elements is to twist the thread upon itself, which causes it tobecome entangled and form a knot or similar obstruction, the passage ofwhich between said tension elements without causing the thread to breakdepends largely upon the strength of the thread and the degree oftension given it. To overcome this difliculty and facilitate the passageof such obstructions, the thread-ten sion elements are formed andmounted so that they are free to rotate, and the thread is passed acrossthe tensioning surfaces thereof at one side of their diameter, whichform of construction gives to said elements either a rotary or anon-rotary relationship with respect to the passing thread, dependentupon the condition of the latter.

In the accompanying drawings illustrating the invention, in the severalfigures of which like parts are similarly designated, Figure 1 is a viewin perspective of the head and the front end portion of a sewing machinebracket arm, the latter being equipped with the improved mechanismtogether with a preferred form of coacting threadtensioning andthread-controlling mechanism, such as is commonly employed in connectionwith the improved mechanism when the latter is applied to machinesoperated by mechanical power at high speed. Fig. 2 is a View in 5central section of the hollow tension stud,

together with full-line Views of the cylindrical thread-tension disksand thread-tension spring. Fig. 3 is a perspective view of the hollowthread-tension stud positioned so as to bring to view itsintegrally-formed thread-guide. Fig. 4 is a view similar to Fig. 3,showing the solid portion of the hollow tension stud uniting the mainportion with that carrying the thread-guide.

1 represents the front end portion of the sewing machine bracket arm, 2the head of said arm, 3 the preferred form of threadtensioning andthread-controlling mechanism used in connection with the present i11-vention, 4 the commonly employed needlecarrying bar and 5 thecloth-presser-carrying bar.

6 represents the hollow thread-tension stud adjustably secured by screw7 in an opening 8 which is formed in the boss 9 carried by the arm 1,said stud being provided with a thread-guide 10 and thread-slot 11. Thecylindrical thread-tension disks 12 and 13 are loosely mounted in thestud 6 with the end wall or thread-tensioning surface 14 of the disk 13resiliently held by the thread-tension spring 15 against thethread-tensioning wall 16 of the. disk 12, the end 17 of said springcontacting with the bottom wall (not shown) of the opening 8.

The slot 11 passes through suflicient of the diameter of the stud 6 topermit the thread 18 to pass between the disks 12 and 13 at one side oftheir diameter, the thread being led through the eye 10 and in contactwith the end wall 19 of the slot 11, as shown in Fig. 1. Under ordinaryconditions, the thread will pass between the tensioning surfaces withoutproducing any substantial movement of the tension disks, but when a knotor similar obstruction enters, its action on a point at one side of thediameter of said disks causes the latter to turn and in doing sorelieves the thread of the excessive strain incident to the action oftension disks which are held against movement in substantially the samedirection as the travel of the thread.

Claim:

In a tension device adapted to act on a running thread, the combinationof a hollow thread-tension stud provided with a threadguide and athread-slot, cylindrical threadtension disks loosely mounted in saidstud and having their thread tensioning surfaces in alinernent With saidthread-guide and In testimony whereof, I have signed my thread-guideslot, the line connecting the name to this specification, in thepresence of thread-guiding portions of said thread-guide two subscribingWitnesses.

and thread-slotpassing at one side of the FRANK S. WVOODHEAD. 5 axis ofsaid disks, and means for resiliently \Vitnesses:

holding said thread-tensioning surfaces in ABBIE D/I. DONIHEE,

abutting relationship. ALBERT M. WOLFE.

Gopies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. G.

